The present invention relates generally to apparatus for filtering particulate matter from a fluid flow, and more particularly pertains to the structure of a system for filtering radioactive particles from coolant associated with a nuclear reactor.
It is common practice in a nuclear power plant to utilize demineralized water in a coolant pool as a heat transfer medium around the core of the reactor. It is also common for the pool water to be contaminated by corrosive by-products, taking the form of fine radioactive particles. These particles are commonly referred to in the industry as "CRUD", an anacromyn for Clinch River Unidentified Deposits, a term coined in the industry to describe the usually black or gray highly radioactive particles that were first noted in the very early experimental light water reactors, most notably at the Clinch River facility of the Tennessee Valley Authority. Such CRUD deposits are a primary source of occupational radiation exposure in a nuclear facility and pose a continuing problem that must be dealt with by continuous filtration.
Other systems have been devised for filtration removal of particulate matter from the nuclear reactor coolant fluid. Representative of apparatus of such a system is the subject matter disclosed in U.S. Pat. No. 3,890,233 and in U.S. Pat. No. 4,883,588. A common problem associated with such systems involves the procedure for exchange or change-out of filter cartridges which are designed to entrain the particulate matter from the coolant processed through the cartridge media. Once a filter cartridge has accumulated and entrained a high density of radioactive particles, handling the spent cartridge and its safe removal is a severe problem due to its intense concentration of CRUD and its associated high radiation level.
Despite systems for particulate filtration that have been contributed by the prior art, there remains a need for apparatus for coolant filtration in a nuclear facility capable of containing a multiplicity of disposable filter cartridges disposed within a containment vessel to simultaneously receive contaminated coolant which is cleansed by the filters and expelled back to its pool of origin, and to provide such apparatus with the capability of relatively rapid and safe filter cartridge exchange during apparatus shut-down.
In other non-nuclear industries, systems have been provided for multiple cartridge filtration of fluids used in food, chemical, pharmaceutical, and general manufacturing industries. The apparatus of such a system is disclosed in U.S. Pat. No. 4,257,888, however, such a system does not address the specific problems associated with personal exposure to high levels of radiation emitted from the concentration of CRUD, also known as Radwaste, collected by the use of high-efficiency filtering media.
Accordingly, it is a general objective of this invention to provide improved apparatus for filtration of radioactively contaminated coolant of a nuclear reactor.
It is also an objective of the present invention to provide such coolant filtration apparatus that is capable of significantly extended filtration run time and which can be rapidly and safely serviced during non-operative down time and then quickly restored to its functioning mode.
It is a further objective of the present invention to provide apparatus for radioactive particulate filtration which uses a significantly large number of commercially available filter cartridges to simultaneously obtain an improved high level of particle removal efficiency.
Other objectives and desirable characteristics of the present invention will become apparent from the ensuing detailed description of the invention when read in reference to the accompanying drawings.